Positive temperature coefficient characteristics of poly(3-alkylthiophene)s

Yamauchi, Takeshi; Najib, Hamid; Liu, Y.W.; Shimomura, Masato; Miyauchi, Shinnosuke

doi:10.1016/s0379-6779(97)80866-1

Cited by 9 publications

(8 citation statements)

References 2 publications

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“…D increases with the temperature increase at the low-temperature region and then i \ I , I , I , I , I slightly decreases at T >1 Te. An analogous dependence with the characteristic temperature Te ~ 150 K was obtained for dc conductivity of P3HT [74] typical for the systems with a strong coupling of the charge with the lattice phonons. In this case, the strong temperature dependence of the hopping conductivity is more evidently displayed in the ac conductivity.…”

Section: Ac Conductivity Of P30tsupporting

confidence: 64%

EPR study of spin and charge dynamics in slightly doped poly(3-octylthiophene)

Krinichnyi

Roth

2004

Appl. Magn. Reson.

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An initial virgin plasticine-like poly(3-octylthiophene) (P3OT) and this sample modified by annealing and recrystallization were investigated at X-band (10 GHz) and mainly at D-band (140 GHz) electron paramagnetic resonance (EPR) in a wide temperature region. Paramagnetie centers with anisotropic magnetic-resonance parameters were proved to exist in all polymers, namely, mobile polarons whose concentration and susceptibility depend on the temperature and the polymer treatment. Superslow torsional motion of the polymer chains and layers was studied by the saturation transfer method at D-band EPR. Spin-spin and spin-lattice relaxation times were measured separately by the steady-state saturation method at the same waveband EPR. Intrachain and interchain spin diffusion coefficients and conductivity due to polaron dynamics were calculated. It was shown that the charge transport in P3OT is determined by the strong spin-spin interaction and is stimulated by torsion motion of the polymer chains. The total conductivity of P3OT is determined mainly by dynamics of paramagnetic charge carriers. Magnetic, relaxation and dynamics parameters of P3OT were also shown to change during the polymer treatment.

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Section: Ac Conductivity Of P30tsupporting

confidence: 64%

EPR study of spin and charge dynamics in slightly doped poly(3-octylthiophene)

Krinichnyi

Roth

2004

Appl. Magn. Reson.

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“…The conductivity of the composite containing TiC of 90 wt %, which was similar to that of TiC, almost did not change over the range of temperatures from −50 to 220°C. On the other hand, the conductivity of the composites with the TiC content < 60 wt %, which was similar to that of P3HT, presented a PTC effect near the melting point of P3HT (200°C) 8, 15. However, in the case of the composite with the TiC content of 70–80 wt %, which was slightly higher than the percolation threshold, the conductivity changed drastically by about four orders of magnitude between 10 −1 and 10 −5 S cm −1 in the vicinity of room temperature.…”

Section: Resultsmentioning

confidence: 81%

“…The materials having PTC characteristics can be used to manufacture self‐limiting heating cables and various switching devices (for example, overcurrent protectors or resettable fuses) 6, 7. In our previous studies, the PTC characteristics of cast films of P3HT, which was synthesized at a low temperature by chemically oxidative polymerization, were investigated 8. Although the P3HT cast film showed a significant PTC effect near the melting point, there still exists some difficulty in applying it to electric devices because of its low conductivity at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Temperature-conductivity characteristics of the composites consisting of fractionated poly(3-hexylthiophene) and conducting particles

Liu

Oshima

Yamauchi

et al. 2000

J. Appl. Polym. Sci.

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Poly (3‐hexylthiophene) (P3HT) synthesized by oxidative polymerization was fractionated by molecular weight by using organic solvents. The fraction of higher average molecular weight gave higher regioregularity and conductivity. Composites of the P3HT fraction having the highest molecular weight were prepared by use of the following conducting particles as fillers: titanium carbide (TiC), indium tin oxide (ITO), and carbon black (CB). Temperature‐conductivity profiles of the composites showed that the resistance change with PTC (positive temperature coefficient) effect was strongly influenced by the content and size of conducting particles and the molecular weight of P3HT. Although no significant PTC effect for P3HT‐CB composite and little effect for P3HT‐ITO composite system were observed, the P3HT‐TiC composite containing TiC of 70–80 wt % showed an obvious PTC effect that brought the conductivity change by about four orders of magnitude near the glass transition temperature of P3HT. However, such a remarkable PTC effect was not observed for the P3HT‐TiC composite prepared with the P3HT fraction of low‐molecular weight. It was shown that a good PTC effect could be achieved by the composite consisting of the P3HT of high‐molecular weight and the conducting particles of relatively large size. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3069–3076, 2000

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“…Dedoped poly(3‐hexylthiophene) (P3HT) shows reproducible switching characteristic of conductivity due to a conjugation length change of the thiophene backbone caused by a dramatic disturbance of the hexyl chain during the melting and is promising for the fabrication of devices with a positive temperature coefficient (PTC) effect 2. The conductivity–temperature characteristics of intrinsic P3HT and its composites mixed with various conducting particles have been reported in previous studies 3–7. The results have demonstrated that the PTC effect of composites is greatly influenced by the dispersion state of filler particles in the P3HT matrix, which is actually determined by the mixing method and the properties of the filler particles.…”

Section: Introductionmentioning

confidence: 79%

Preparation of a poly(3‐hexylthiophene)‐grafted indium tin oxide/poly(3‐hexylthiopene) composite and its conductivity–temperature characteristics

Liu

Oshima

Shimomura

et al. 2006

J of Applied Polymer Sci

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ABSTRACT:The temperature-conductivity characteristics of poly(3-hexylthiophene) (P3HT) composites filled with P3HT-grafted indium tin oxide (ITO) particles were investigated in this work. The ITO particles were first treated with a silane coupling reagent of 3-aminopropyltriethoxysilane (APS), and then thiophene rings were introduced through a condensation reaction between the ending amino groups of APS and the carboxylic groups of thiophene-3-acetic acid. The composites were prepared by the polymerization filling of the 3-hexylthiophene (3HT) monomer with the thiophenering-introduced ITO particles. Elemental analysis, Fourier transform infrared, and X-ray photoelectron spectroscopy were used to confirm the grafting reaction on the ITO surface. The longer the polymerization time was or the higher the 3HT/ITO feeding ratio was, the more P3HT was grafted. The influence of the grafted amount on the electrical properties of ITO particles was attributed to the wrapping effect formed by the grafted P3HT on the surface of the ITO particles. The conductivity change of the P3HT-grafted ITO/ P3HT composites was proved to be subject to the change in the average gap width of ITO interparticles, which was determined by the filling ratio of P3HT to ITO in the polymerization and the volume expansion effect of a P3HT thin film between neighboring ITO particles during the heating process. In comparison with the ungrafted ITO/P3HT composites, the grafting treatment enhanced the interaction between the particles and polymer matrix, and this was helpful for obtaining a more homogeneous dispersion structure for the composites and thus afforded a higher positive temperature coefficient intensity and better reproducibility.

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Positive temperature coefficient characteristics of poly(3-alkylthiophene)s

Cited by 9 publications

References 2 publications

EPR study of spin and charge dynamics in slightly doped poly(3-octylthiophene)

EPR study of spin and charge dynamics in slightly doped poly(3-octylthiophene)

Temperature-conductivity characteristics of the composites consisting of fractionated poly(3-hexylthiophene) and conducting particles

Preparation of a poly(3‐hexylthiophene)‐grafted indium tin oxide/poly(3‐hexylthiopene) composite and its conductivity–temperature characteristics

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